csky: convert to setup_initial_init_mm()

Use setup_initial_init_mm() helper to simplify code.

Link: https://lkml.kernel.org/r/20210608083418.137226-6-wangkefeng.wang@huawei.comSigned-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/csky/kernel/setup.c

@@ -78,10 +78,7 @@ void __init setup_arch(char **cmdline_p)
 	pr_info("Phys. mem: %ldMB\n",
 		(unsigned long) memblock_phys_mem_size()/1024/1024);
 
-	init_mm.start_code = (unsigned long) _stext;
-	init_mm.end_code = (unsigned long) _etext;
-	init_mm.end_data = (unsigned long) _edata;
-	init_mm.brk = (unsigned long) _end;
+	setup_initial_init_mm(_stext, _etext, _edata, _end);
 
 	parse_early_param();